Devonian Burrows? Fish Poo?

[BenWorrell]

ID help please!

 

I recently found these strange features in a Devonian rock in Johnson County, Iowa. They are unusual looking enough that I suspect an animal may have been involved in their formation. My first guess was that they were burrows that had filled in with dense crinoid and shell debris, but I'm not sure how that would happen. My second guess was that it could be poop/coprolite from a fish or some other Devonian creature. I didn't have a scale with me, but these would be very large for fish poop. I will post another photo in a separate post below (files are too big). I would be very grateful for any assistance, thank you!

 

Here is a link to a video that may also be helpful: 

 

 

[BenWorrell]

Here's a close-up photo

[minnbuckeye]

Interesting! I lean towards infilled burrow tubes, but take my thoughts with a grain of salt. 

 

Mike

[BenWorrell]

1 minute ago, minnbuckeye said:

Interesting! I lean towards infilled burrow tubes, but take my thoughts with a grain of salt. 

 

Mike

Thanks for the input Mike. Any idea what sort of creatures made burrows in the Devonian? Maybe trilobites or something?

[Rockwood]

I'm not sure it qualifies as poop, but maybe processed sediment ? Imagine something like a sea cucumber ingesting crinoid mush and expelling the inedible. 

[Norki]

Maybe rip-up clasts? They look like they could be storm-tossed chunks of clay that resettled into new sediments.